When exporting a dxf to Rhino I noticed that drawing one triangle counter clockwise and another clockwise does not make any difference regarding the direction of their normals. Like this:

import processing.dxf.*;

void setup(){
  size(500,500, P3D); 
}

void draw(){
  beginRaw(DXF, "output.dxf");
 
  beginShape();
  vertex(0,0,0);
  vertex(100,100,-10);
  vertex(0,100,0);
  endShape(CLOSE);
 
  beginShape();
  vertex(100,0,0);
  vertex(100,100,0);
  vertex(200,100,-10);
  endShape(CLOSE);

  endRaw();
  exit();
}

Any way to get control over the normals? Another lib maybe? (I am trying to draw something for a 3D printer)